JPS5826500B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-frequency heating device for heating an object using radio wave energy, and more particularly to a means for controlling the heating of an object to be heated by the device.

It is well known that radio energy in the microwave band is used to heat objects.

A common configuration of such high-frequency heating devices is a configuration in which radio waves emitted from a radio wave generation source such as a magnetron are supplied directly or through a waveguide to the inside of a cavity called an oven in which the object to be heated is housed. belongs to.

In the apparatus having such a configuration, the heating time of the object to be heated is usually controlled by a timer such as a timer.

In this case, it is necessary to adjust the heating time appropriately depending on the type of the object to be heated, that is, the difference in dielectric loss coefficient, the weight, and the rice temperature, that is, the temperature of the object to be heated before heating.

If the time adjustment is inappropriate, the result will be that the object to be heated is undercooked or overcooked.

Conventionally, as a solution to this problem, a temperature sensing element is inserted into the object to be heated, the temperature of the object to be heated is directly detected, and the oscillation of the magnetron is controlled to control the heating of the object to be heated. methods are being used.

In the device having such a means, the object to be heated loses its shape,
This may cause damage by interfering with cooking.

SUMMARY OF THE INVENTION Therefore, the present invention aims to provide a means for controlling the heating of an object to be heated, regardless of the type, weight, or rice temperature of the object to be heated, and which does not cause deformation of the object.

More specifically, it is desired to detect a physical change in the air flow passing through the cavity and control a radio wave generation source using the signal to control the heating of the object to be heated, and to reliably configure such a means. There is an aim of the present invention.

Examples will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is the main body of the device, and 2 is a door attached to the main body 1 so as to be openable and closable.

The main body 1 has a cavity 3 as shown in FIG. 2, and a door 2 is disposed to close an entrance/exit (not shown) of the cavity 3 for the object to be heated.

In FIGS. 2 and 3, 4 is a magnetron that is a radio wave generation source.

Reference numeral 5 denotes a blower for cooling the magnetron 4. The blower 5 is surrounded by an air guide 7, and the air guide 7 is provided with a blower intake port 6.

8 is an exhaust air guide for cooling the magnetron 4, and 9 is an antenna cover that surrounds the antenna section of the magnetron 4.

The antenna cover 9 is made of a dielectric material with low loss at high frequencies.

10 is a rotating saucer, and the heated object 1 is placed in the rotating saucer 10.
3 is placed, and the rotating saucer drive motor 11 is used as a drive source,
The coupling piece 12 connects the rotary saucer drive motor 11
The driving force of
It is configured to rotate around l as the center of rotation.

14 is an intake duct, and 15 is an intake opening formed in the cavity 3.

The wind entering the cavity 3 is introduced into the cavity 3 via the intake duct 14 and through the intake opening 15 .

Reference numeral 16 denotes an exhaust opening disposed in the cavity 3, and the exhaust opening is constituted by a metal pipe 21 in order to prevent interference radio waves.

17 is an exhaust duct.

The wind leaving the cavity 3 passes through the exhaust opening 16 to the exhaust duct 1
It is exhausted through 7.

One end of the exhaust duct 17 is disposed near the blower intake port 6 so that the intake force of the blower 5 acts on the exhaust duct 17.

Reference numeral 18 denotes a detection element that detects physical changes in wind, that is, airflow, and in this embodiment, an element such as a thermistor that is sensitive to temperature changes in the airflow is used.

19 is an amplification means for amplifying the signal of the detection element 18;
20 is operated by the output generated from the amplification means 19;
This is a control means for controlling the oscillation of the magnetron 4.

Reference numeral 22 denotes a control valve that is a means for adjusting the flow rate of the airflow passing through the detection element 18 , and the control valve 22 is operated by a valve driving section 23 .

The valve drive unit 23 maintains a constant flow rate of the airflow flowing back to at least the sensing element 18, since the rotational speed of the blower 5 differs depending on the power frequency of 50 Hz and 60Hz, and the flow rate of the airflow to be sent out differs. It corresponds to the driving part of a solenoid valve that can adjust the opening angle of the control valve 22 to be large at 50 Hz and small at 60 Hz by external operation depending on the power frequency.

Next, the operation of the above embodiment and the effects of each part will be explained.

Radio waves generated by the magnetron 4 are radiated into the cavity 3 and heat the object 13 to be heated.

The object to be heated 13 rotates together with the rotating tray 10 and is uniformly heated.

As the heating of the object to be heated 13 progresses, the object to be heated 13
The radiant heat radiated from increases.

This heat is transferred to the sensing element 18 by the wind passing through the cavity 3.

The air sent to the cavity 3 is sent by the blower 5, but the rotation speed of the blower 5 varies depending on the power frequency and cannot send a constant amount of air. Therefore, the valve drive unit 23 is operated by external operation, and the control valve By adjusting the opening angle of 22 to be large at 50 Hz and small at 60 Hz, the airflow flowing back to at least the portion of the sensing element 18 is kept constant.

The detection element 18 generates a signal in response to a change in the radiant heat of the object 13 to be heated.

The signal generated from the sensing element 18 is amplified by the amplification means 19 and transmitted to the control means 20.

Therefore, when the object to be heated reaches a desired temperature, the control means 20 is activated, the oscillation of the magnetron 4 is controlled, and the heating of the object to be heated is controlled.

The present embodiment operates as described above.

Incidentally, the first feature of this embodiment is that the heating of the object to be heated is not controlled by a timer.

Therefore, since it is not necessary to adjust the heating time, it becomes possible to control the heating of the object to be heated to a desired temperature regardless of the type, weight, and temperature of the rice to be heated.

The second feature is that it is a so-called indirect detection method that detects temperature changes of the heated object without directly inserting the sensing element 18 into the heated object, so the heated object does not lose its shape. be.

The third characteristic is the uniqueness of the wind path.

That is, as described above, the flow rate of the airflow passing through the sensing element 18 is adjusted.

Fluctuations in the flow rate of the airflow passing through the sensing element 18 cause a significant disturbance to the sensing element 1B.

Factors that change the flow rate of airflow include 50Hz, 60Hz,
Differences in power supply frequency in Hz have a significant effect on fluctuations in the rotational speed of the blower 5, and have a fatal effect on detection accuracy.

However, in the present invention, this problem can be avoided by using a means for adjusting the flow rate, so that accurate heating control can be performed.

In order to faithfully carry out the gist of the present invention, it is necessary to automatically operate the valve drive unit 23 to open and close the control valve 22 in accordance with the flow rate of the airflow.

However, as shown in FIG. 4, it is also possible to provide an adjustment piece 24 in a removable manner in the airflow path, that is, in the intake duct 14, just to avoid fluctuation factors due to differences in power supply frequency.

As described above, according to the present invention, it is possible to control the heating of the object to be heated without deforming the object, regardless of the type of the object to be heated or the weight and rice temperature, and the means for doing so can be reliably configured. A high frequency heating device can be provided.

In addition, in the embodiment, a configuration was presented in which the oscillation of the magnetron is controlled by capturing the temperature change of the airflow passing through the cavity, but the configuration is not necessarily limited to such a configuration.
For example, the idea of the present invention can also be applied to a structure in which the heating of the object to be heated is controlled by controlling the oscillation of a magnetron using other physical changes such as changes in the humidity of airflow due to water vapor generated from the object to be heated. Needless to say, it can be done.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a high-frequency heating device according to the present invention,
FIG. 2 is a schematic vertical cross-sectional view of the main part, and FIG. 3 is a schematic cross-sectional view of the main part. FIG. 4 is a schematic vertical cross-sectional view of the main part of another embodiment. 3... Cavity, 4... Magnetron, 5... Blower, 18... Detection element, 22... Control valve, 23...
Valve drive unit, 24...adjustment piece.

Claims (1)

[Claims] 1 has a cavity 3 for storing an object to be heated, has an opening through which the airflow passes, and has a detection element 18 near the outlet side of the airflow that detects a physical change in the airflow. A high-frequency heating device characterized in that it is equipped with an adjustment means to keep the flow rate of the airflow passing through the detection element 18 almost constant without changing the rotational speed of the blower even if the power supply frequency changes. .